<!DOCTYPE html>
<html>

<head>
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <style>
        #snackbar {
            visibility: hidden;
            min-width: 250px;
            margin-left: -125px;
            background-color: #333;
            color: #fff;
            text-align: center;
            border-radius: 2px;
            padding: 16px;
            position: fixed;
            z-index: 1;
            left: 50%;
            bottom: 30px;
            font-size: 17px;
        }

        #snackbar.show {
            visibility: visible;
            -webkit-animation: fadein 0.5s, fadeout 0.5s 2.5s;
            animation: fadein 0.5s, fadeout 0.5s 2.5s;
        }

        @-webkit-keyframes fadein {
            from {
                bottom: 0;
                opacity: 0;
            }

            to {
                bottom: 30px;
                opacity: 1;
            }
        }

        @keyframes fadein {
            from {
                bottom: 0;
                opacity: 0;
            }

            to {
                bottom: 30px;
                opacity: 1;
            }
        }

        @-webkit-keyframes fadeout {
            from {
                bottom: 30px;
                opacity: 1;
            }

            to {
                bottom: 0;
                opacity: 0;
            }
        }

        @keyframes fadeout {
            from {
                bottom: 30px;
                opacity: 1;
            }

            to {
                bottom: 0;
                opacity: 0;
            }
        }
    </style>
</head>

<body>

    <h2>Snackbar / Toast</h2>
    <p>Snackbars are often used as a tooltips/popups to show a message at the bottom of the screen.</p>
    <p>Click on the button to show the snackbar. It will disappear after 3 seconds.</p>

    <button onclick="myFunction()"     style="padding: 25px;">Show Snackbar</button>

    <div id="snackbar">Some text some message..</div>

    <script>
        function myFunction() {
            var x = document.getElementById("snackbar");
            x.className = "show";
            setTimeout(function () { x.className = x.className.replace("show", ""); }, 3000);
        }
    </script>



    <xmp style="font-size: 22px; font-weight: bolder;  margin-bottom: 66px;  color: black;  font-family: '微软雅黑';">

        必知必会

        三秒后消失:
        setTimeout(function () { x.className = x.className.replace("show", ""); }, 3000);

        #snackbar.show {
            visibility: visible;
            -webkit-animation: fadein 0.5s, fadeout 0.5s 2.5s;
            animation: fadein 0.5s, fadeout 0.5s 2.5s;
        }

        @keyframes fadein {
            from {
                bottom: 0;
                opacity: 0;
            }

            to {
                bottom: 30px;
                opacity: 1;
            }
        }

        @keyframes fadeout {
            from {
                bottom: 30px;
                opacity: 1;
            }

            to {
                bottom: 0;
                opacity: 0;
            }
        }


    </xmp>
  

 
</body>

</html>